It has been conventional practice to fabricate industrial steel drums with at least the bottom end having a five ply closure. With the increase in the cost of steel as well as its scarcity, it has become desirable to construct drums of thinner gauge metal. However, the standard five ply end closure in many instances will not be sufficiently strong, sturdy and durable to withstand the contemplated and normal use and abuse as well as prescribed governmental testing, i.e. rupturing or otherwise failing under standard drop tests.
In the past, a conventional technique employed for many years, in the manufacture of steel drums, barrels and containers of the industrial variety initially formed a cylinder of sheet steel, rolled, welded, or mechanically joined along its longitudinal edges. The cylinder was then flanged at both ends in a press or rolling machine. This flanged cylinder was then stiffened with two or more rolling hoops or stiffening corrugations around its circumference at strategic locations. This cylinder could also be flanged at one one end and beaded or rolled at the other for providing open mouth containers.
On a machine known in the trade as a double seamer, the cylinder with the flanged ends was then assembled at each end to a flanged, steel closure in the form of stamping with various circumferential corrugations or strengthening ribs around its periphery to provide the bottom and top head of the container. In the full open mouth design, a bottom would be formed in this manner and the top provided with a reasonable cover or lid.